The present invention relates to a wheel rotating device for rotating a wheel of an automobile, and more particularly to a brake structure for a wheel rotating device which can reduce the size of the structure.
In-wheel motor for driving a wheel of an automobile is arranged in a limited space of the wheel. In recent years, attempts have been made to design layout of various parts so that the size of the whole device can be reduced while increasing the diameter of the motor for improving motor torque. For example, Japanese Laid-open Patent Application No. 2004-114858 discloses such a layout design. As a brake structure for the wheel rotating device, hydraulic brake is generally used so that a large braking force is obtained.
Japanese Laid-open Patent Application No. 2004-114858 discloses an in-wheel motor equipped with a hydraulic braking mechanism. According to this arrangement, an externally attached hydraulic pressure tube consisting of a brake hose is connected between a hydraulic pressure supply source to be fixed to the vehicle body and a braking device of a wheel. This brake hose is arranged so as to extend along the periphery of a motor housing.
However, since the brake hose extends along the motor housing and is attached externally, it is necessary to ensure mounting space for externally attached parts at the outer peripheral side of the motor. This makes it difficult to increase the diameter of the motor, and as a result, torque of the motor cannot be increased. Further, it is difficult to layout the brake hose.
In view of the above, the present invention seeks to provide a brake structure for a wheel rotating device which can eliminate the drawbacks as above, and which can reduce the size of the braking mechanism including a fluid passage (i.e., brake fluid passage) for brake application.